An agricultural harvester e.g., a plant cutting machine, such as, but not limited to, a combine or a windrower, generally includes a header operable for severing and collecting plant or crop material as the harvester is driven over a crop field. The header has a plant cutting mechanism, e.g., a cutter bar, for severing the plants or crops via, for example, an elongate sickle mechanism that reciprocates sidewardly relative to a non-reciprocating guard structure. After crops are cut, they are collected inside the header and transported via a conveyor such as a draper belt towards a feederhouse located centrally inside the header.
Epicyclical cutter bar knife drives oscillate first and second sickle mechanisms of cutter bars in opposite directions in order to cut crop. However, conventional epicyclical knife drives generate moments and/or other forces that can lead to stresses in the knife drives as well as at the connections of the driver elements to the cutter bar. In addition, by virtue of their horizontal orientation with vertical output shafts, they are prone to accumulation of dirt and debris which leads to degradation of seals and premature wear of gears and other components.